quantum dotabbr., QD; NDotherwise nano-dot
(rus. квантовая точкаabbr., КТ)
— particle of a material, whose size is close to the wavelength of an electron in such material (usually 1-10 nm); the electron potential energy in such particle is lower than outside of it, therefore motion of the electron is limited in all three dimensions.

-Fine particles of semiconductors, either colloidal or deposited on a porous carrier, 1-30 nm in diameter.

The electronic spectrum of an ideal quantum dot is a set of discrete levels, separated by regions of forbidden states; it formally corresponds to an electronic spectrum of a single atom. However, the real quantum dot can consist of hundreds of thousands of atoms. The minimum and maximum sizes of quantum dots depend on their substance; for example, in the system InAs-AlGaAs the minimum size of quantum dots is 4 nm and their maximum size shall not exceed 30 nm.

Illustrations

A section of Si(100) surface with a dimple ~100 nm in diameter and 16 nm deep having a quantum dot at the bottom represented by a thin layer of Ge atoms. On the right - cross profile of the dimple with the quantum dot sized ~30 nm in diameter and 1.5 nm in height.